diff --git a/README.md b/README.md
index 9879e40..8f94278 100644
--- a/README.md
+++ b/README.md
@@ -205,7 +205,8 @@ Please be aware that mark does not validate the layout, so it's your responsibil
 ### Placeholders
 
 You can use this to define placeholders:
-```
+
+```markdown
 <!-- ac:placeholder -->
 Placeholder
 <!-- ac:placeholder end -->